Colonic Sterilization for NOTES Procedures – a Comparison of Two Decontamination Protocols

Introduction:In the 2005 White Paper, prevention of infection was named as one of the ten potential barriers to performing NOTES surgery. The aim of this study was to evaluate the effect of two different sterilization protocols on the bacterial counts in the swine colon while preparing for NOTES surgery.Methods:After placing a proximal colon balloon, 16 swine were randomized to two different colonic sterilization protocols. Protocol 1 consisted of low colonic irrigation with 300cc of a 1:1dilution of 10% povidone-iodine (Betadine) with sterile saline, followed by one gram of cefoxitin dissolved in 300cc of saline. Protocol 2 consisted of 2 consecutive 300cc irrigations utilizing a quaternary ammonium antimicrobial (Onamer M). Colonic cultures were taken at 3 time-points; before colonic cleansing, after decontamination protocol and after NOTES procedure completion. The Invitrogen Live/Dead bacterial viability kit was used to asses for change in bacterial load. A qualitative culture of peritoneal fluid was obtained at the end of the NOTES procedure. Colon mucosal biopsies were obtained immediately after the sterilization procedure and at the 2-week necropsy point, and were evaluated for mucosal changes. Student’s T-test was used for statistical comparisons.Results:Protocol 1 resulted in an average 80.8% decrease in live colonic bacteria, versus 83.0% in Protocol 2 (NS). After performing a NOTES colonic procedure, Group 1 had a104.4% increase in live bacteria and Group 2 a 36.2% increase (NS). Peritoneal cultures were also obtained after trans-colon endoscopic examination. Bacteria were isolated from the peritoneal fluid of all animals and 2 or more species were isolated from 75% of the animals. There was no evidence of peritoneal infection at necropsy. Half of the mucosal specimens had mild changes immediately after sterilization but these were equally distributed between both decontamination protocols. Reactive epithelial changes and mild inflammation were only abnormalities. No changes were noted on histologic evaluation of colonic mucosa at the 2 week point, demonstrating these were temporary changes.Conclusion:Colonic irrigation with Betadine and antibiotics are as effective at bacterial decontamination of the swine colon as a quaternary ammonium compound. The results of this study support the use of either protocol. Despite thorough decontamination, peritoneal contamination occurs. The significance of this for humans is unknown.